Pulverizing apparatus

ABSTRACT

A pulverizer of the type having a rotating lower ring engaged by a plurality of roller elements engaging a wear surface on the face of the ring, and the roller elements are rotated as a unit in the opposite direction to that of the ring about a common axis of rotation. Each roller element is supported by a driven ring with the assembly resiliently driven from a drive ring.

United States atent 1191 1111 3,73,44 6 Piepho 1 May 1, 1973 154] PULVERIZING APPARATUS 3,658,264 4/1972 Schauer ..241 121 1,834,094 12/193] Fraser [75] lnvemcr' f wadswmh 2,815,903 12/1957 Crites ..241/1 18 Medma County, Ol'llO [73] Assignee: The Babcock & Wilcox Company, Primary ExaminerDonald G. Kelly New York, NY. Attorney-J. Magquire [22] Filed: Oct. 21, 1971 [57] ABSTRACT [21] Appl' 19l263 A pulverizer of the type having a rotating lower ring engaged by a plurality of roller elements engaging a [52] US. Cl. ..24l/ll0, 24 Ill 18, 241/121 wear surface on the face of the ring, and the roller ele- [51 Int. Cl ..B02c 4/02 ments are rotated as a unit in the opposite direction to [58] Field of Search; ..241/l 10, 1 l8, 120, that of the ring about a common axis of rotation. Each 24l/l21, 127-133 roller element is supported by a driven ring with the assembly resiliently driven from a drive ring. [56] References Cited 6 Claims, 3 Drawing Figures UNITED STATES PATENTS R25,552 1 1 1641 Berz ..24l/ll8 V" 54 A 57 35L r: 58

4o I J as 3] 1 2e 41 l l I ll Q is 3'2 PATENTED H975 3,730,446

SHEET 1 [IF 2 INVENTOR Roberf R. Piepho PATENTED 1 I975 sum 2 [IF 2 PULVERIZING APPARATUS The invention relates to improvements in the .construction and operation of pulverizers, and more particularly to pulverizers of the ring and roll type where both the ring and the roll assembly are rotated in opposite directions about an upright common axis.

In the present invention a pulverizer of the described type is provided where a lower ring having an upwardly facing annular grinding surface is rotated about an upright axis. A circumferential series of rolls are mounted above the lower ring in grinding relation thereto for rotation as a unit about an axis common to that of the ring and in an opposite direction. Each individual roll is separately supported for rotation about its own axis and arranged for separate adjustment under resilient pressure to effectively cooperate with the grinding surface of the lower ring for e fficient pulverization of the raw materials delivered to the pulverizer.

Of the drawings:

FIG. 1 is an elevation, partly in section, of a pulverizer constructed and arranged according to the invention;

FIG. 2 is an enlarged elevation view partly in section of a part of the pulverizer shown in FIG. 1; and

FIG. 3 is an end view of a portion of the pulverizer shown in FIG. 2.

In general, the pulverizer illustrated includes a cylindrical upper housing section and a lower housing section 11 supported on a foundation 12. The sections 10 and 11 are fastened together for ease of assembly, and the section 10 may be made in two cylindrical portions 13 and 14 for ease of access to the grinding and classification zones hereinafter described. The lowerfrom a motor or motors, not shown. Any suitable drive mechanism capable of rotating the shafts may be used. One suitable drive mechanism is disclosed in US. Pat. No. 3,093,327. The interaction of the lower ring 18 and the roller assembly 20 pulverizes raw material delivered thereto, defining a grinding zone 16.

Air, at superatmospheric pressure, enters the lower section 14 of the pulverizer housing 10 through an encircling duct 21, to pass upwardly adjacent the outer side or periphery of the grinding zone 16, entraining comminuted coal, and thence through a classifier or separator 22 with the air-borne finished product leaving the pulverizer housing 10 through a centrally located upper outlet 23. The oversized material is passed downwardly from the separator 22 into a vaned annular discharge port 24 for return to the pulverizing zone 16. i

The grinding zone of the pulverizer includes a lower horizontally disposed grinding ring 18 having an annular groove or race 26 formed in its upper face. The

lower grinding ring 18 is provided with a flat lower face supported on and pinned to a T-shaped annular ledge member 30 and to the annular upper surface of a generally conical driving rotor 28, the shank 32 of the member 30 being interposed between the ring 18 and the rotor 28. The rotor 28 is affixed to the upper end portion of the shaft 15 which is rotated by the drive mechanism (not shown).

As shown in FIG. 1, the generally vertical arms 31 of the member 30 extend above and below the shank 32. The upper arm of the member 30 forms an upstanding ledge to restrict the flow of pulverized material from the grinding zone 16, while the outer surface 33 of the arm is shaped to cooperate with a vertically adjustable stationary ring member 36 in defining a throat 37 for directing the upward flow of entraining airpast the grinding zone 16. As shown the cooperating surfaces defining the throat 37 direct the entraining air upwardly and slightly outwardly toward the housing section 14 of the pulverizer. Thus, the air passing through the duct 20 enters the pulverizer housing section 14 through a vaned annular opening 38 discharging in an inward direction. into a chamber 40 and thence upwardly through the throat. The chamber 40 is inwardly defined by the upper and lower arms 35 and 41, respectively of the rotating member 30, and at the top by the lower portion of member 36, and in part by the throat 37. The ring 36 may be provided with a spring loaded displaceable section (not shown) which will be forced outwardly toward the housing by foreign materials such as tramp iron, or the like in the grinding 16'. Such foreign materials will fall by gravity into chamber 40 and discharge downwardly into a box (not shown), from which the materials may be periodically removed. r The mixture of pulverized material and air passing upwardly in an annular stream adjacent the inner wall of the housing sections 13 and 14 enters the classifier 22 through a series of circumferentially disposed angularly positioned upright vanes 42 located downwardly adjacent the upper plate 43 forming the top of the pulverizer housing. The vanes 42 are attached to the plate 43 and are provided with adjustable end portions 44 which may be extended or retracted to alter the fineness characteristics of the finished product. The lower edges of the vanes 42 are attached to the base flange of an inverted frustoconical member 45 extending downwardly to the annular opening 24 for the discharge of separated coarser solid materials from the classifier 22. The opening 23 in the top of the pulverizer is provided with a depending duct 46 extending downwardly into the classifier and thereby providing an outlet for air-borne classified material to leave the pulverizer housing 10. The lower end of the duct 94 may be provided with an adjustable cylindrical member which embraces the duct 94 and may be vertically adjustable for a relatively minor regulation of the fineness limits of the materials discharged from the pulverizer.

As shown, the inner side of the lower annular classifier discharge opening 24 is defined by a cylindrical cap member 47 which is attached to the shaft 17 through a yoke 54 (hereinafter described) and rotates therewith. The cap member protects the upper end of the shaft, and the yoke 54 attachment to the shaft, and provides a support for a vaned rotor 48 operating in the opening 24 to reduce the back flow or leakage of airborne materials upwardly through the opening.

The roller drive assembly 20 includes a circumferentially equally spaced series of rolls 50 each resiliently mounted from and driven by the shaft 17, as hereinafter described. In the usual installation three or four rolls 50 are installed, depending upon pulverization requirements, although more than three or four rolls may be used. Each roll 50 is mounted for rotation with its outer surface crowned to generally conform in configuration with the wear surface 26 of the lower ring 18.

As shown in FIGS. 1, 2 and 3 each roll 50 is mounted on an axle 51 with suitable bearings interposed between the roll and its axle to permit rotation therebetween. In the construction shown the axle 51 is attached to a bracket 52 so that the axis of rotation of the roll is inclined downwardly in an inward direction with respect to the axis of rotation of the coaxial shafts and 17. The upper end surface of the bracket is detachably secured to an annular support or driven ring 53. With each of the rollers connected with the ring 53 through their individual brackets the entire assembly is driven in rotational movement from the shaft 17 by a drive arrangement hereinafter described.

A yoke 54 is detachably connected with a hub 55 which is rigidly attached to the upper end portion of the shaft 17 and locked in keyed relation thereto by a nut 56. The yoke 54 is formed with an inner annular portion attached to the hub 55 by bolts 57 and is provided with radially extended circumferentially equally spaced portions or arms 58 which corresponds in number with the rolls 50, as constructed for any particular installation.

As shown in the drawings, each driving arm extension 58 is detachably fixed to the annular driving ring 60 so as to transmit rotational force thereto. The arm extensions 58 are each provided with machined parallel surfaces 61 and 62 positioned to be above the ring 60 as shown particularly in FIGS. 2 and 3. The arm extension (see FIG. 3) is mounted on the ring 60 by an adjusting bolt 64 which extends through the extension 58 to the ring 60, and is further reinforced by a strong back bar 65 straddling the arm and provided with tie bolts 66 attached to the ring 60. The ring 60 is provided with inwardly extending blocks 70 and 71 positioned to generally horizontally enclose the surfaces 61 and 62 of arm 58. The circumferential relationship between the arm 58 and the matching surfaces of blocks 70 and 71 is maintained by a set screw 67 so as to insure equality of driving forces from the arms 58 to the rollers 50.

Depending members 70 and 71 provide a direct driving relation to the ring 55. As shown in FIG. 3, the ring 55 is provided with an inwardly projecting lug 72 which engages the surfaces of blocks 70 and 71 to transmit rotational force to the ring 55 from the driving arm. Wear surfaces 73 are fixed to the surfaces of blocks 70, 71, and lug 72. The structure permits vertical movement between the driven ring 55 and the ring 60 while transmitting rotational force therebetween.

As shown, generally in FIG. 1, and more specifically in FIGS. 2 and 3 the resilient attachment between the drive ring 60 and the driven ring 55 includes a pair of coiled springs 74 and 75 which are closely disposed on opposite sides of a radial plane intersecting the center line of the driving arm 58 and the axis of rotation of the roll 50. The springs are seated on the ring 55, extend through the ring 60 and are adjustably positioned relative to the ring 60 by adjustable upright bolts 76 which are attached to the driving ring 60. Thus, the compressive force exerted by the springs on the ring 55 may be adjusted by manipulation of the position of the upper end of the coil springs as effected through a plate 77 which is held in place by adjustable nuts 78 mounted on the upright bolts 76. The effect of the spring construction is to permit the adjustable application of compression force on the rollers 50.

The connection between the drive ring 60 and the driven ring 53 must be resilient and flexible so as to permit the application of a selected pressure on the rollers and to compensate for unusual movements and wear in the roller assembly 20. It will be noted the drive ring 60 is located in a generally fixed horizontal plane, as determined by the structural supports of the drive shaft 17. It will also be noted that each roller in its grinding cooperation with the grinding ring 24 will be subjected to varying movements and stresses due to grinding of materials of different hardnesses and size, necessitating relative vertical movement between the grinding ring and its associated rollers. The vertical movements of the rollers need not necessarily by synchronized.

In FIG. 1 the connection between the ring 55 and brackets 52 indicates a fixed, but detachable connection therebetween. This fixed relationship between bracket and ring is operable and maintains a fixed angular relationship between the rolls 50 and the grinding ring 18. Preferably, as shown in FIGS. 2 and 3 the ring 55 and the bracket 52 may be provided with a hinge adjacent the inner edge of the bracket so as to permit a restricted angular change radially of the shafts 15 and 17, between the grinding ring and the rollers 50.

As shown in FIGS. 2 and 3 the hinge construction includes a groove 80 machined in the lower surface of the ring 55 and the upper surface of the bracket 52 adjacent the inner edge of both. The groove in each surface has a cross-section shape in the form of a segment ofa circle to accommodate a segmental rod 81 extending substantially the horizontal length of the upper surface of the bracket. The segmental rod 81 inserted in the matching grooves is formed in 3 pieces with preferably longitudinally extending overlapping portions which permits relative rotation between the segments. As shown in FIG. 3, the outer end segments 82 (only one shown) of the rod forming the hinge are bolted as at 83 to the ring 55 while the intermediate or central segment 84 of the rod is bolted as at 85 to the bracket 52.

With the hinge installed as described, the roll assembly 20 is permitted to move in a radial plane common to the axis of shaft 17 and the axis of axle 51.

In operation, the hinged construction permits each of the rolls to move about the axis of the hinge to accommodate unusual conditions in the localized part of the grinding zone, as for example, when tramp material is encountered. The net effect of the use of the hinge reduces stresses on the roll assembly 20 permitting extended life of the roll bearings. From a purely theoretical standpoint, the hinge action on the roll assembly can increase the life of the bearings from 50 to percent as compared with a rigid connection between the ring and the bracket.

What is claimed is:

1. A pulverizer comprising a housing enclosing a grinding zone, a horizontally disposed grinding ring positioned in the grinding zone and having an upwardly facing annular grinding surface, means for rotating said ring about an upright axis, a plurality of rollers circumferentially equally spaced about an upright axis corresponding with the axis of the ring, the rollers being positioned in grinding relation to the grinding surface of the ring, means including a shaft for rotating the rollers about the upright axis in a direction opposite to the direction of rotation of the ring, the improved structure for mounting said rollers including a yoke attached to said shaft and having circumferentially equally spaced arms with the arms extending radially outwardly of the shaft and spaced above said grinding ring, an annular driving ring detachably secured to the arms of the yoke in a substantially horizontal position, an annular driven ring spaced beneath and driven in rotational movement by the driving ring, the driven ring being resiliently mounted for vertical movement relative to said driving ring, each roller being supported for rotation on an axle mounted in a bracket, the axle being inclined downwardly and inwardly with respect to the axle of ring rotation and lying in a plane radial with respect to the axis of ring rotation the bracket being attached to said driven ring.

2. A pulverizer according to claim 1 wherein the attachment between the driven ring and the bracket includes a hinge positioned perpendicular to the radial plane containing the axis of roller rotation.

3. A pulverizer according to claim 2 wherein said hinge construction forms a space between the adjacent surfaces of the driven ring and the bracket.

4. A pulverizer according to claim 3 wherein a stop bolt between the adjacent surfaces of the drive and the driven rings limit the relative movement therebetween.

5. A pulverizer according to claim 1 wherein the resilient mounting between the driving and driven rings includes an upright coil spring closely positioned on each side of the radial plane common to the axis of rotation of each roller about its supporting axle.

6. A pulverizer according to claim 5 wherein the radially extended arms of the yoke are each provided with circumferentially spaced driving surfaces depending to the level of said driving ring to provide for vertical adjustment between yoke and driving ring, and the driven ring is provided with inwardly extending lugs engaging opposing wear surfaces of the driving ring to allow vertical movement therebetween and to apply rotational force from the yoke to the driven ring. 

1. A pulverizer comprising a housing enclosing a grinding zone, a horizontally disposed grinding ring positioned in the grinding zone and having an upwardly facing annular grinding surface, means for rotating said ring about an upright axis, a plurality of rollers circumferentially equally spaced about an upright axis corresponding with the axis of the ring, the rollers being positioned in grinding relation to the grinding surface of the ring, means including a shaft for rotating the rollers about the upright axis in a direction opposite to the direction of rotation of the ring, the improved structure for mounting said rollers including a yoke attached to said shaft and having circumferentially equally spaced arms with the arms extending radially outwardly of the shaft and spaced above said grinding ring, an annular driving ring detachably secured to the arms of the yoke in a substantially horizontal position, an annular driven ring spaced beneath and driven in rotational movement by the driving ring, the driven ring being resiliently mounted for vertical movement relative to said driving ring, each roller being supported for rotation on an axle mounted in a bracket, the axle being inclined downwardly and inwardly with respect to the axle of ring rotation and lying in a plane radial with respect to the axis of ring rotation, the bracket being attached to said driven ring.
 2. A pulverizer according to claim 1 wherein the attachment between the driven ring and the bracket includes a hinge positioned perpendicular to the radial plane containing the axis of roller rotation.
 3. A pulverizer according to claim 2 wherein said hinge construction forms a space between the adjacent surfaces of the driven ring and the bracket.
 4. A pulverizer according to claim 3 wherein a stop bolt between the adjacent surfaces of tHe drive and the driven rings limit the relative movement therebetween.
 5. A pulverizer according to claim 1 wherein the resilient mounting between the driving and driven rings includes an upright coil spring closely positioned on each side of the radial plane common to the axis of rotation of each roller about its supporting axle.
 6. A pulverizer according to claim 5 wherein the radially extended arms of the yoke are each provided with circumferentially spaced driving surfaces depending to the level of said driving ring to provide for vertical adjustment between yoke and driving ring, and the driven ring is provided with inwardly extending lugs engaging opposing wear surfaces of the driving ring to allow vertical movement therebetween and to apply rotational force from the yoke to the driven ring. 